[sarahj]

Grab the source, compile it and get it running...after that...whatever you find interesting. Some ideas:

* Trace the execution of one of the user land programs (e.g. ls) to see how it uses the syscalls.

* Add a new syscall - there are a few open-courseware labs online which have this as in introductory exercise (e.g http://moss.cs.iit.edu/cs450/assign01-xv6-syscall.html)

* In a similar vein - find some other labs for other courses using this - and follow them.

* Read through the companion book (can be compiled from the source or downloaded pre-compiled) and follow it through the source code.